function Base64() {
   this._keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
}

Base64.prototype.encode = function(input) {
   var output = "";
   var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
   var i = 0;

   //input = this._utf8_encode(input);

   while (i < input.length) {

      chr1 = input.charCodeAt(i++);
      chr2 = input.charCodeAt(i++);
      chr3 = input.charCodeAt(i++);

      enc1 = chr1 >> 2;
      enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
      enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
      enc4 = chr3 & 63;

      if (isNaN(chr2)) {
          enc3 = enc4 = 64;
      } else if (isNaN(chr3)) {
          enc4 = 64;
      }

      output = output +
      this._keyStr.charAt(enc1) + this._keyStr.charAt(enc2) +
      this._keyStr.charAt(enc3) + this._keyStr.charAt(enc4);

   }

   return output;
}

Base64.prototype.decode = function(input) {
   var output = "";
   var chr1, chr2, chr3;
   var enc1, enc2, enc3, enc4;
   var i = 0;

   input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

   while (i < input.length) {

      enc1 = this._keyStr.indexOf(input.charAt(i++));
      enc2 = this._keyStr.indexOf(input.charAt(i++));
      enc3 = this._keyStr.indexOf(input.charAt(i++));
      enc4 = this._keyStr.indexOf(input.charAt(i++));

      chr1 = (enc1 << 2) | (enc2 >> 4);
      chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
      chr3 = ((enc3 & 3) << 6) | enc4;

      output = output + String.fromCharCode(chr1);

      if (enc3 != 64) {
          output = output + String.fromCharCode(chr2);
      }
      if (enc4 != 64) {
          output = output + String.fromCharCode(chr3);
      }

   }

   //output = this._utf8_decode(output);

   return output;
}

Base64.prototype._utf8_encode = function (string) {
  string = string.replace(/\r\n/g,"\n");
  var utftext = "";

  for (var n = 0; n < string.length; n++) {

      var c = string.charCodeAt(n);

      if (c < 128) {
          utftext += String.fromCharCode(c);
      }
      else if((c > 127) && (c < 2048)) {
          utftext += String.fromCharCode((c >> 6) | 192);
          utftext += String.fromCharCode((c & 63) | 128);
      }
      else {
          utftext += String.fromCharCode((c >> 12) | 224);
          utftext += String.fromCharCode(((c >> 6) & 63) | 128);
          utftext += String.fromCharCode((c & 63) | 128);
      }

  }

  return utftext;
}

// private method for UTF-8 decoding
Base64.prototype._utf8_decode = function (utftext) {
  var string = "";
  var i = 0;
  var c = c1 = c2 = 0;

  while ( i < utftext.length ) {

      c = utftext.charCodeAt(i);

      if (c < 128) {
          string += String.fromCharCode(c);
          i++;
      }
      else if((c > 191) && (c < 224)) {
          c2 = utftext.charCodeAt(i+1);
          string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
          i += 2;
      }
      else {
          c2 = utftext.charCodeAt(i+1);
          c3 = utftext.charCodeAt(i+2);
          string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
          i += 3;
      }

  }

  return string;
}
